That was my first thought, @zerenia, before I noticed the multiplication symbol snuck in there …then there’s a specific order of operations to follow when computations aren’t grouped inside parentheses…

As @ctgolfer pointed out, 4, 6, and 7 won’t fill: 4 and 6 will stay completely dry, while 7 would only see water IF water were to come out of the spigot faster than it could drain into 3, at which point, it would continually drain out the bottom of 7, thereby knocking 2 out of the running, as well)…

However, 5 will stay dry, as well, as the pipe leading up to it is capped… (I missed it, too, when initially viewing the diagram on a mobile device )

Therefore, 3 will fill up first; as there is no lid, once it is full, the water will flow over the edge into the abyss below…